TECHNICAL AND ECONOMIC ASSESSMENT OF CARBON DIOXIDE CAPTURE FROM ETHANOL PRODUCTION PLANTS FOR HYDROMETHANE PRODUCTION IN PARAGUAY Marcelo Barboza Torresa, Advisors: Dr. Gustavo Riverosb, M.SC. Ing. Aldo Mendietac aUniversidad Católica "Nuestra Señora de la Asunción" - Campus Alto Paraná, Facultad de Ciencias y Tecnología b Centro de Innovación en automatización y Control – FPTI Paraguay c Universidad Nacional de Asunción, Facultad de Ingeniería [email protected], [email protected], [email protected] Introduction This research was developed within the project Hydromethane (ETEPHM) faced by FPTI-Paraguay, where the main topic being the CO2 capture from sugar-distilleries plants distributed throughout the Paraguay. The viability study is presented considering the capture of the carbon dioxide from generated during the fermentation in the ethanol production process from a technical and an economic point of view, and then use the CO2 to synthesize methane , following the principle of the Sabatier reaction, reacting hydrogen and the captured carbon dioxide at high temperatures and pressures to transform them, using a catalyst, into water and methane. (the hydrogen required is obtained by water electrolysis). Experimental tests conducted by [1] found a final composition of 64% CH4, 29 % H2 and 7% CO2 in volume terms. Whereby the resultant methane can be described as hydromethane, due to the presence of hydrogen gas. H2 content should not exceed 30%, to avoid problems both in the transport and combustion. Objective The main objective was to evaluate the technical and economic viability of capturing the CO2 emitted during the fermentation of sugar cane distilleries plants in Paraguay as an input to be used in the synthesis of a potential fuel capable of replacing the natural gas called hydromethane (mixture of hydrogen and methane), referencing certain scenarios developed under the current situation of the department of Alto Paraná, Paraguay.

Another project that uses the same concept proposed in this work for the Methodology synthesis of hydromethane is the E-Gas project from Audi. The Company is Different CO2 capture systems were found in the literature, being chosen the establishing a portfolio of sustainable energy sources by producing a system shown in the Figure 1, referencing [2], it includes the necessary data to sustainable fuel, the E-Gas (synthetic methane) [3], in which it is proposed to perform the technical and economic analysis. use renewable electricity (generated by wind or solar), water and carbon dioxide to synthesize the E-Gas. The plant produces the E-Gas in two stages,

electrolysis and methanation, as shown in Figure 2 In the first stage, the

electrolyser separates water into hydrogen and oxygen. In the second stage of the process, hydrogen is reacted with the CO2 to produce synthetic methane.

The carbon dioxide used by Audi gas plant comes from the exhaust of a biomethane plant adjacent, although this scheme is represented by CO2 emissions from human activities, such as transport and housing.

Figure 1. Schematic of the CO2 capture plant considered in this work Source: [2] (Illinois State Geological Survey, 2006)

The stoichiometric reaction for the conversion of glucose into ethanol yields 0.511 grams of ethanol and 0.489 grams of carbon dioxide per gram of glucose, from which it can be deduced the amount of CO2 generated for every liter of ethanol. However industrial performance normally reach about 87% of efficiency. In this paper the proportion that each liter of ethanol produced, is considerer in 0.55 kg of CO2 per liter of ethanol.

This paper considers the catalytic hydrogenation of the captured CO2 (also Figure 2. Schematic of the production process of the E-Gas known as the Sabatier reaction) to synthetize methane, the Sabatier reaction Source: [3] (Audi e-gas project, 2014) states that it is necessary 5.5 kg of CO2 for each kg of H2 in order to obtain the stoichiometric composition of methane [2], or in other words, in order to produce each kg of CH4 it is necessary 0.5 kg of H2 and 2.75 kg of CO2. Results and Conclusions In order to estimate the viability from the economic point of view, the unit cost of CO2 capture per ton is calculated, this cost is directly related to the equipment installation and operation costs, as shown in the Equation Power requirement of the Equipment from the 푪푨푪푶ퟐ 푪푪푶ퟐ = CO2 capture plant 푷푨푪푶ퟐ 5% 푪 =unit cost of CO2 capture (US$/ton); 푪푨푪푶ퟐ=annual cost of CO2 capture (US$/year) 푪푶ퟐ 39% CO2 Compressor 푷푨푪푶ퟐ= Annual CO2 generation in the ethano plant (ton/year) 56% NH3 Compressor

The annual carbon capture cost is given by: Auxiliary Equipment

푪푨푪푶ퟐ = 푪풊 + 푪푶푴 + 푪풊풏풔 + 푪푮푮푬

Figure 3. Schematic of the CO2 capture plant considered in this work 푪풊=Annual investment cost (US$/year); 푪푶푴=Annual operation&maintenance cost (US$/year) Source: [2] (Illinois State Geological Survey, 2006) 푪푮푮푬 = Greenhose Gas Emissions costs (US$/year); 푪풊풏풔=Inputs cost (US$/year) The study assumes CDE (Ciudad del Este, Paraguay) as the impact area and 1. As shown in Figure 3 the equipment with the highest energy impact (hence includes 25% and 50% of all gasoline-fueled vehicles (about 29,800 vehicles) scenarios A and B respectively. Table 1 shows the data taken into account for economic) in the capture system is the CO2, so it can be concluded that the analysis of each scenario according to the Sabatier Reaction, which states in order to optimize the capture process is necessary to optimize the that for each kg of CH4 are needed 2.75 kg of CO2. operation of the compressors. 2. The main result of this paper expresses a capture cost of 15.49 US$/ton Table 1. Data for each scenario Source: Own Elaboration and 30.98 US$/ton for scenarios A and B respectively, demonstrating technical feasibility but not necessarily an economic viability, simply because the cost of CO2 capture found in both scenarios it is not Scenario CO2 (kg/year) Hydromethane (kg/year)1 Vehicles within the range of the reference capture costs found in the literature[4-6], as shown in Figure 4 A 24.591.050 8.942.200 14.904 3. Yet it is important to note that when considering a larger amount of B 12.295.525 4.471.100 7.452 CO2 the capture cost decreases, making the proposal more interesting. Proving that it is viable when considering the economy of 1 Considering an average consumption of 4 kg/day hydromethane, with an average scale. consumption of 600 kg of hydromethane/year by vehicle 120

References 100

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[4] Xu, Y., Isom, L., & Hanna, M. (2010). Adding value to carbon dioxide from 20 ethanol fermentations. Bioresource technology, 101(10), 3311-3319. various sources( [5] Electric Power Research; WorleyParsons Services Pty Ltd; Global CCS

estimates Cost for capturing CO2 from Institute. (2009). Strategic Analysis. Report 4: Existing Carbon Capture and 0 Storage Research. Power plant IGCC power Hydrogen Ammonia Natural gas Refinery flue Cement Steel Plants Ethanol [6] Carbon Capture and Storage. (s.f.). Recuperado el 15 de Junio de 2014, de boiler flue gas plant Plants Plants processing gas Plants Plants Center for Climate and Energy Solutions: Figure 3. CO2 capture costs from various sources http://www.c2es.org/technology/factsheet/CCS Source : Own Elaboration